Conventionally, there is known a silicon carbide (SiC) sintered body obtained by forming a SiC powder and then sintering the formed SiC powder. The SiC sintered body is used in many fields because of excellent heat resistance, thermal shock resistance, corrosion resistance, and high temperature strength property thereof. In addition, the thermal shock resistance means a property that is not easily damaged by sudden temperature changes (thermal shock). In addition, the high temperature strength property means strength in a high temperature region.
In addition, the SiC sintered body exhibits conductivity and is therefore widely used as a resistance heating element. In order to improve the heat generation property of the resistance heating element, development focusing on a specific resistance value of the SiC sintered body has been conducted (for example, Patent Literature No. 1 and Patent Literature No. 2).
Patent Literature No. 1 discloses a method of controlling a specific resistance value of a silicon carbide sintered body. In the method disclosed in Patent Literature No. 1, first, an α-SiC powder having an average particle diameter of 0.1 μm or higher and 10 μm or lower, a β-SiC powder having an average particle diameter of 0.1 μm or higher and 10 μm or lower, and a SiC ultrafine powder having an average particle diameter of lower than 0.1 μm and synthesized in a gas phase by plasma CVD are mixed in a desired ratio to obtain a SiC mixed powder. Next, the specific resistance value of the silicon carbide sintered body can be controlled in a wide range of about 1.0×10−3 to 1.0×102 Ω·cm by heating and sintering the obtained SiC mixed powder.
Patent Literature No. 2 discloses a method for producing a conductive SiC sintered body which exhibits easy control of resistance at the time of production and has a relative density of 90% or higher.
In the production method disclosed in Patent Literature No. 2, a mixture of a SiC powder having an average particle diameter of 2 μm or lower and a sintering aid is formed into a formed body, and the formed body is heated and sintered at a temperature of 2100° C. to 2300° C. in an inert atmosphere containing 30 to 90% by volume of nitrogen gas. B compounds such as B, B4C, and BN, and carbon sources such as carbon black and phenol resin are used as the sintering aid. Thereby, a conductive SiC sintered body having properties of a specific resistance value of 10 Ω·cm or lower and a relative density of 90% or higher is obtained in the production method disclosed in Patent Literature No. 2.